The Brain Tumor Cooperative Group (BTCG) has performed a series of controlled prospective randomized trials in patients with malignant gliomas, which have established the state-of-the-art of the multimodality treatment of this disease consisting of extensive surgical resection, high-dose radiation therapy (RT) and adjuvant chemotherapy. It is proposed to continue these studies as follows: I. To increase good-quality survival by performing Phase III and Phase II clinical trials. To perform a new Phase III trial based on the concept of Induction of Remission, which will utilize interstitial radiation therapy as part of the RT modality. This Trial (87-01) randomizes newly diagnosed patients to (a) receive postoperative temporary 1241 seed implantation in the residual tumor bed, followed by standard external beam RT plus IV BCNU, or (b) to receive external RT plus BCNU, without the seed implantation. The trail will test the value of adding interstitial radiation to the previously established best available therapy regimen. The Phase II, Scheme A trail randomizes previously resected and radiated Nonprogressive patients and Progressive patients without prior chemotherapy to (a) intracaratid (IC) Cisplatin or (b) IV PCNU. The Phase II, Scheme B trial tests the value of intramuscular interferon in the treatment of Progressive patients who have failed initial therapy, including chemotherapy. To test a new system of RT quality control based on CT scan measurements. II. To plan and perform a new Phase III trial (87- 30) in patients with low-grade gliomas to determine the value of RT along with surgical resection in the treatment of this disease. III. To investigate the tumor-host biology of human gliomas, including their presentation and evolution in relationship to CT and MRI scans, prognostic variables and histopathological changes over time. IV. To study acute and long-term consequences of therapy including early and late RT/chemotherapy neurological effects assessed by CT, MRI, clinical, psychometric and pathological changes, and non-neurological effects.